The present invention relates to a friction lining, in particular for use in brakes, clutches and other applications, having mineral fibres which contain alumina, Al.sub.2 O.sub.3, silica, SiO.sub.2, and lime, CaO.
In friction linings of this type, it has already been proposed to use slag fibres and also basalt fibres as mineral fibres.
In general, slag fibres have a precentage by weight of alumina, Al.sub.2 O.sub.3, of between 10% and 15%, a percentage by weight of silica, SiO.sub.2, of between 38% and 45% and a percentage by weight of lime CaO, of between 35% and 45%, while basalt fibres have a percentage by weight of alumina, Al.sub.2 O.sub.3, of between 10% and 20%, a percentage by weight of silica, SiO.sub.2, of between 38% and 46% and a percentage by weight of lime, CaO, of between 10% and 18%.
The applicants have found that friction linings containing slag fibres are relatively brittle in contrast to friction linings containing basalt fibres, which frequently have an excessive aggressiveness towards the counter-material, such as the disc, ring, drum or plate, with which the friction lining interacts by rubbing.
Experiments carried out by the applicants have shown that the proportion of lime, CaO, in the mineral fibres is of prime importance in determining the brittleness and the aggressiveness of the friction lining.
The relatively high percentage of lime, CaO, of between 35% and 45% in slag fibres would explain the brittleness of linings containing slag fibres, while the relatively low percentage of lime, CaO, of between 10% and 18% in basalt fibres would explain the aggressiveness towards the counter-material of friction linings containing basalt fibres.
Experiments have shown that mineral fibres having a smaller proportion of lime, CaO, than in the case of slag fibres, but a higher proportion thereof than in the case of basalt fibres have the effect of substantially reducing the brittleness and also the aggressiveness of the friction lining.
The present invention relates to a friction lining, in particular for brakes, clutches and other applications, having mineral fibres which contain alumina, Al.sub.2 O.sub.3, silica, SiO.sub.2, and lime, CaO, and which possess excellent rubbing characteristics and good properties as regards both the robustness and the absence of aggressiveness towards the counter-material.